1. Field of the Invention
The present invention relates to a method of improving hydrocarbon production from a reservoir that was completed with a gravel pack, wherein fine particles that clog the gravel pack are removed from the gravel pack so that hydrocarbon production is increased.
2. General Background of the Invention
Formations that exhibit a tendency to release formation particles during hydrocarbon production (commonly called “sanding” or “fines migration”) create problems as these particles are released into the hydrocarbon stream. Particles can bridge in formation flow channels and impede production rate. Particles carried into a well bore with produced hydrocarbon can also erode well structure such as tubulars and well heads. Such particles can settle into the bottom of a well bore and impede production.
Common practice for completing wells drilled into high-permeability formations with sanding tendency through the early 1990's was to install a tubular wire screen into the well bore and gravel pack the space between the screen and casing or bore hole wall. Gravel packing is still a preferred completion method for many low budget wells drilled into high-permeability formations with sanding tendencies.
The gravel packing operation includes a transport of sand into the space between the screen and the casing, and into the perforation tunnels. The sand is sized to prevent fine particles or fines from the specific formation from passing through the pack (usually 20-40 mesh or 30-50 mesh or 40-60 mesh). The sand is deposited into the annulus behind the screen and then packed to create a filter to stop the fine particulate matter or fines from migrating into the well bore. The screen openings are further sized to act as a final filter for any fines migrating through the sand bed. Thus, the problems of producing from sanding formations are mitigated.
This gravel pack type of completion method always damages the permeability of the formation compared to native permeability of the reservoir rock. Additionally, as fines migrate into the well and are trapped by the gravel pack, permeability is further reduced resulting in reduced production rates.